Semiconductor memory with local phase generation from global phase signals and local isolation signals

ABSTRACT

A Dynamic Random Access Memory (DRAM) eliminates the need to route section signals to local phase drivers to generate local phase signals by gating local isolation signals and global phase signals together in the local phase drivers to generate the local phase signals. As a result, the die &#34;footprint&#34; of the DRAM is reduced.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of application Ser. No. 09/083,606,filed May 22, 1998, pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates in general to semiconductor memories and, morespecifically, to semiconductor memories in which local phase signals aregenerated in local phase drivers using global phase signals and localisolation signals, thus eliminating the need to route section signals tothe local phase drivers.

2. State of the Art

As shown in FIG. 1, a conventional Dynamic Random Access Memory (DRAM)10 includes multiple 256 Kilobit (KB) sub-arrays 12 accessed using evenand odd row decoders 14 and 16, sense amplifiers 18, gap circuitry 20,center circuitry 22, and address circuitry 24. More specifically,accessing one of the sub-arrays 12 begins when the address circuitry 24receives a memory address (not shown) and outputs section signalsSECTION, global isolation signals GISO, and global phase signals GPH inresponse. Referring to FIG. 2 for a moment, the center circuitry 22receives the section signals SECTION and the global isolation signalsGISO and gates them together in local isolation (LISO) circuitry 26 toproduce local isolation signals LISO. Referring now to FIG. 3, the gapcircuitry 20 receives the section signals SECTION and the global phasesignals GPH and gates them together in local phase drivers 28 to producelocal phase signals LPH. The local phase signals LPH are then used inconjunction with the memory address (not shown) by one of the rowdecoders 14 and 16 to fire a selected row in one of the sub-arrays 12.Once the selected row is fired, the local isolation signals LISO areused in one of the sense amplifiers 18 in conjunction with the memoryaddress (not shown) to access a selected column in the same sub-array 12as the selected row.

As can be seen in FIG. 1, many signals must be routed to the gapcircuitry 20 and sense amplifiers 18, including the section signalsSECTION, the local isolation signals LISO, and the global phase signalsGPH. These signals use "real estate" on the die on which the DRAM 10 isfabricated, and thus limit the functional circuitry that can beimplemented in the DRAM 10, or increase the necessary size of the die onwhich the DRAM 10 is fabricated. Thus, it would be desirable to reducethe signals routed to the gap circuitry 20 and sense amplifiers 18 inorder to increase the functional circuitry that can be implemented inthe DRAM 10 or decrease the necessary size of the die on which the DRAM10 is fabricated.

Therefore, there is a need in the art for a semiconductor memory havinga reduced number of signals routed to gap circuitry and senseamplifiers.

SUMMARY OF THE INVENTION

A semiconductor memory, such as a Dynamic Random Access Memory (DRAM),in accordance with the invention includes address circuitry forreceiving memory addresses and outputting corresponding section signals,global isolation signals, and global phase signals. Local isolationcircuitry incorporated, for example, into center circuitry of thesemiconductor memory outputs local isolation signals in accordance withthe section signals and the global isolation signals. Local phase signalcircuitry, such as local phase drivers, outputs local phase signals inaccordance with the global phase signals and the local isolationsignals. Row accessing circuitry, such as row decoders, activates rowsin a memory array of the semiconductor memory that are selected inaccordance with the memory addresses and the local phase signals. Columnaccessing circuitry, such as sense amplifiers, accesses columns in thememory array selected in accordance with the memory addresses using thelocal isolation signals.

Thus, the local phase signal circuitry uses the local isolation signalsin combination with the global phase signals to generate the local phasesignals, in contrast to the conventional practice previously described,in which local phase drivers use section signals in combination with theglobal phase signals to generate the local phase signals. By eliminatingthe use of the section signals to generate the local phase signals, theinvention eliminates the need to route the section signals to the localphase drivers, and thus reduces the die "footprint" of the semiconductormemory.

In other embodiments of the invention, the above described semiconductormemory is incorporated into an electronic system and is fabricated onthe surface of a semiconductor substrate, such as a semiconductor wafer.

In still another embodiment of the invention--a method of accessing amemory array in a semiconductor memory--memory addresses are provided tothe semiconductor memory, and section signals, global isolation signals,and global phase signals are then generated in accordance with thememory addresses. The section signals and global isolation signals aregated together to generate local isolation signals, and the localisolation signals and global phase signals are then gated together togenerate local phase signals. With the local phase signals generated,rows in the memory array selected in accordance with the memoryaddresses and the local phase signals are activated, and columns in thememory array selected in accordance with the memory addresses areaccessed using the local isolation signals.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of a conventional Dynamic Random Access Memory(DRAM) in which section signals are routed to local phase drivers insense amplifier gap circuitry to generate local phase signals;

FIG. 2 is a more detailed view of the center circuitry of FIG. 1;

FIG. 3 is a more detailed view of the sense amplifier gap circuitry ofFIG. 1;

FIG. 4 is a block diagram of a DRAM in accordance with the presentinvention in which local isolation signals and global phase signals areused to generate local phase signals;

FIG. 5 is a more detailed view of the sense amplifier gap circuitry ofFIG. 4;

FIG. 6 is a block diagram of an electronic system incorporating the DRAMof FIG. 4; and

FIG. 7 is a diagram of a semiconductor wafer on which the DRAM of FIG. 4is fabricated.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 4, a Dynamic Random Access Memory (DRAM) 40 inaccordance with this invention includes multiple 256 Kilobit (KB)sub-arrays 42 accessed using even and odd row decoders 44 and 46, senseamplifiers 48, gap circuitry 50, center circuitry 52, and addresscircuitry 54. Although this invention will be described with referenceto the DRAM 40, it will be understood by those having skill in thetechnical field of this invention that it is applicable not only toDRAMs, but also to a wide variety of other semiconductor memories. Also,it will be understood that this invention may be implemented using awide variety of semiconductor memory architectures other than that shownin FIG. 4, and that the scope of the present invention is limited onlyby the claims.

Accessing one of the sub-arrays 42 begins when the address circuitry 54receives a memory address (not shown) and outputs section signalsSECTION, global isolation signals GISO, and global phase signals GPH inresponse. The center circuitry 52 receives the section signals SECTIONand the global isolation signals GISO and gates them together to producelocal isolation signals LISO. Referring for a moment to FIG. 5, the gapcircuitry 50 receives the local isolation signals LISO and the globalphase signals GPH and gates them together in local phase drivers 58 toproduce local phase signals LPH. Referring again to FIG. 4, the localphase signals LPH are then used in conjunction with the memory address(not shown) by one of the row decoders 44 and 46 to fire a selected rowin one of the sub-arrays 42. Once the selected row is fired, the localisolation signals LISO are used in one of the sense amplifiers 48 inconjunction with the memory address (not shown) to access a selectedcolumn in the same sub-array 42 as the selected row.

Because the local phase drivers 58 (FIG. 5) gate the local isolationsignals LISO together with the global phase signals GPH to determinewhich local phase signals LPH are activated, the section signals SECTIONdo not need to be routed to the gap circuitry 50. Thus, the extensiverouting of section signals to gap circuitry and sense amplifiers foundin conventional DRAMs (see FIG. 1) is avoided. As a result, thisinvention allows the DRAM 40 to use less "real estate" on the die onwhich it is fabricated.

As shown in FIG. 6, an electronic system 60 includes an input device 62,an output device 64, a processor device 66, and a memory device 68incorporating the DRAM 40 of FIG. 4. Of course, it will be understoodthat the DRAM 40 of FIG. 4 may be incorporated into any one of theinput, output, and processor devices 62, 64, and 66 too.

As shown in FIG. 7, the DRAM 40 of FIG. 4 is fabricated on the surfaceof a semiconductor wafer 70 in accordance with this invention. Ofcourse, it should be understood that the DRAM 40 may be fabricated onsemiconductor substrates other than a wafer, such as aSilicon-on-Insulator (SOI) substrate, a Silicon-on-Glass (SOG)substrate, and a Silicon-on-Sapphire (SOS) substrate.

Although this invention has been described with reference to particularembodiments, the invention is not limited to these describedembodiments. Rather, the invention is limited only by the appendedclaims, which include within their scope all equivalent devices ormethods that operate according to the principles of the invention asdescribed.

What is claimed is:
 1. A semiconductor memory comprising addresscircuitry coupled to at least one center circuitry by a section signalline, a global isolation line and a global phase signal line, the atleast one center circuitry further coupled to at least one gap circuitryby at least one local isolation signal line and at least one globalphase signal line, the at least one gap circuitry detached from thesection signal line.
 2. A local phase driver of a gap circuit in asemiconductor memory, the local phase driver comprising:at least onelocal isolation signal input; at least one global phase signal input;and at least one local phase signal output, the inputs and at least oneoutput configured to produce, in combination, at least one local phasesignal in response to receiving at least one local isolation signal andat least one global phase signal.
 3. A method of producing a local phasesignal comprising:receiving at least one local isolation signal and atleast one global phase signal at a gap circuitry; gating the at leastone global phase signal with the at least one local isolation signal;and generating at least one local isolation signal in response to gatingthe at least one global phase signal with the at least one localisolation signal.
 4. The method of claim 3 further comprising:receivingat least one section signal and at least one global isolation signal ata center circuitry; gating the at least one section signal with the atleast one global isolation signal; and generating the at least one localisolation signal in response to gating the at least one section signalwith the at least one global isolation signal.
 5. The method of claim 4further comprising:receiving memory addresses at address circuitry; andgenerating the at least one section signal, the at least one globalisolation signal and the at least one global phase signal in response toreceiving memory addresses.
 6. The method of claim 3, wherein gating theat least one global phase signal with the at least one local isolationsignal comprises using at least one local phase driver to gate thesignals.